A hydraulic gerotor device includes a stator having internal teeth and a rotor having external teeth. The rotor is mounted eccentrically within the stator. There is one more internal tooth on the stator than external teeth on the stator. The internal teeth of the stator can be formed by cylindrical rollers, which reduce wear in the gerotor device between the rotor and the stator.
The cylindrical rollers fit into roller pockets found in the stator. It is known to form these pockets by broaching. A great degree of precision is needed in the final inside diameter of the roller pockets, and it is also desirable to harden the inside diameter of each roller pocket since the inside diameter acts as a bearing surface for the cylindrical rollers. Typically, the internal bearing surface of each roller pocket covers an arc of 180° around the respective roller received therein.
It is also known to hone the roller pockets in a stator. A plurality of similar individual tapered abrasive hones are passed through roller pockets cut into a stator. The hones have outer frusto-conical surfaces and rotate about an axis parallel with a central axis of the stator. The honing process produces adequate results; however, honing requires a highly skilled machine operator.